Dark Energy and its Discontents

Posted in Uncategorized on April 24, 2015 by telescoper

Just time for a spot of gratuitous self-promotion. I shall be giving a public lecture tonight, Friday 24th April 2015, entitled Dark Energy and its Discontents, at the very posh-sounding Bath Royal Literary and Scientific Institution.
I am just finishing the slides for the talk, and packing some dark energy in my bag to use as a demonstration.
Here is the poster for tonight’s event, which explains all…

Bath_lecture

Perhaps I’ll see the odd reader of this blog there?

Another Awayday..

Posted in Uncategorized on April 23, 2015 by telescoper

Just a quick post to say that I spent today in London with the other Heads of School at Sussex University (or most of them). We met in the British Library Conference Centre, which is next door to St Pancras station. It wasn’t in the library itself, so I wasn’t able to try out the famous echo in the British Library Reading Room…

After leaving that meeting at ten-mile I had another appointment, near this relatively well-known landmark..

image

I won’t divulge the purpose or location of Meeting B as it’s a bit hush-hush, though not in a bad way…

Spring Giddiness

Posted in Poetry with tags , , on April 22, 2015 by telescoper

Today, like every other day, we wake up empty
and frightened. Don’t open the door to the study
and begin reading. Take down a musical instrument.
Let the beauty we love be what we do.
There are hundreds of ways to kneel and kiss the ground.

The breeze at dawn has secrets to tell you.
Don’t go back to sleep.
You must ask for what you really want.
Don’t go back to sleep.
People are going back and forth across the doorsill
where the two worlds touch.
The door is round and open.
Don’t go back to sleep.

I would love to kiss you.
The price of kissing is your life.
Now my loving is running toward my life shouting,
What a bargain, let’s buy it.

Daylight, full of small dancing particles
and the one great turning, our souls
are dancing with you, without feet, they dance.
Can you see them when I whisper in your ear?

All day and night, music,
a quiet, bright
reedsong. If it
fades, we fade.

by Jalāl ad-Dīn Muhammad Rūmī (1207-1273)

 

The Supervoid and the Cold Spot

Posted in Astrohype, Cosmic Anomalies, The Universe and Stuff with tags , , , , , on April 21, 2015 by telescoper

While I was away at the SEPnet meeting yesterday a story broke in the press broke about the discovery of a large underdensity in the distribution of galaxies. The discovery is described in a paper by Szapudi et al. in the journal Monthly Notices of the Royal Astronomical Society. The claim is that this structure in the galaxy distribution can account for the apresence of a mysterious cold spot in the cosmic microwave background, shown here (circled) in the map generated by Planck:

Planck_coldspot

I’ve posted about this feature myself here in the category Cosmic Anomalies.

The abstract of the latest paper is here:

We use the WISE-2MASS infrared galaxy catalogue matched with Pan-STARRS1 (PS1) galaxies to search for a supervoid in the direction of the cosmic microwave background (CMB) cold spot (CS). Our imaging catalogue has median redshift z ≃ 0.14, and we obtain photometric redshifts from PS1 optical colours to create a tomographic map of the galaxy distribution. The radial profile centred on the CS shows a large low-density region, extending over tens of degrees. Motivated by previous CMB results, we test for underdensities within two angular radii, 5°, and 15°. The counts in photometric redshift bins show significantly low densities at high detection significance, ≳5σ and ≳6σ, respectively, for the two fiducial radii. The line-of-sight position of the deepest region of the void is z ≃ 0.15–0.25. Our data, combined with an earlier measurement by Granett, Szapudi & Neyrinck, are consistent with a large Rvoid = (220 ± 50) h−1 Mpc supervoid with δm ≃ −0.14 ± 0.04 centred at z = 0.22 ± 0.03. Such a supervoid, constituting at least a ≃3.3σ fluctuation in a Gaussian distribution of the Λ cold dark matter model, is a plausible cause for the CS.

The result is not entirely new: it has been discussed at various conferences over the past year or so (e.g this one) but this is the first refereed paper showing details of the discovery.

This gives me the excuse to post this wonderful cartoon, the context of which is described here. Was that really in 1992? That was twenty years ago!

Anyway, I just wanted to make a few points about this because some of the press coverage has been rather misleading. I’ve therefore filed this one in the category Astrophype.

First, the “supervoid” structure that has been discovered is not a “void”, which would be a region completely empty of galaxies. As the paper makes clear it is less dramatic than that: it’s basically an underdensity of around 14% in the density of galaxies. It is (perhaps) the largest underdensity yet found on such a large scale – though that depends very much on how you define a void – but it is not in itself inconsistent with the standard cosmological framework. Such large underdensities are expected to be rare, but rare things do occur if you survey a large enough volume of the universe. Large overdensities also arise as statistical fluctuations in large volumes.

Second, and probably most importantly, although this “supervoid” is in the direction of the CMB Cold Spot it cannot on its own explain the Cold Spot; the claim in the abstract that it provides a plausible explanation of the cold spot is simply incorrect. A void can affect the measured temperature of the CMB through the Integrated Sachs-Wolfe effect: photons travelling through such a structure are redshifted as they travel through the underdense region, so the CMB looks cooler in the direction of the void. However, even optimistic calculations of the magnitude of the effect suggest that this particular “void” can only account for about 10% of the signal associated with the Cold Spot. This is a reasonably significant contribution but it does not account for the signal on its own.

This is not to say however that it is irrelevant. It could well be that the supervoid actually sits in front of a region of the CMB sky that was already cold, as a result of a primordial fluctuation rather than a line-of-sight effect. Such an effect could well arise by chance, at least with some probability. If the original perturbation were a “3σ” temperature fluctuation then the additional effect of the supervoid would turn it into a 3.3σ effect. Since this pushes the event further out into the tail of the probability distribution it makes a reasonably uncommon feature look  less probable. Because the tail of a Gaussian distribution drops off very quickly this has quite a large effect on the probability. For example, a fluctuation of 3.3σ or greater has a probability of 0.00048 whereas one of 3.0σ has a probability of 0.00135, about a factor of 2.8 larger. That’s an effect, but not a large one.

In summary, I think the discovery of this large underdensity is indeed interesting but it is not a plausible explanation for the CMB Cold Spot. Not, that is, unless there’s some new physical process involved in the propagation of light that we don’t yet understand.

Now that would be interesting…

SEPnet Awayday

Posted in Education with tags , , , on April 20, 2015 by telescoper

Here I am in Easthampstead Park Conference Centre after a hard day being away at an awayday. In fact we’ve been so busy that I’ve only just checked into my room (actually it’s a suite) and shall very soon be attempting to find the bar so I can have a drink. I’m parched.

The place is very nice. Here’s a picture from outside:

Eastham

I’m told it is very close to Broadmoor, the famous high-security psychiatric hospital, although I’m sure that wasn’t one of the reasons for choice of venue.

I have to attend quite a few of these things for one reason or another. This one is on the Future and Sustainability of the South East Physics Network, known as SEPnet for short, which is a consortium of physics departments across the South East of England working together to deliver excellence in both teaching and research. I am here deputising for a Pro Vice Chancellor who can’t be here. I’ve enjoyed pretending to be important, but I’m sure nobody has been taken in.

Although it’s been quite tiring, it has been an interesting day. Lots of ideas and discussion, but we do have to distil all  that down into some more specific detail over dinner tonight and during the course of tomorrow morning.  Anyway, better begin the search for the bar so I can refresh the old brain cells.

 

Mental Health at Work – to Declare or not to Declare?

Posted in Biographical, Mental Health with tags , on April 19, 2015 by telescoper

I couldn’t resist a comment on a recent article in the Times Higher  (written in response to an earlier piece expressing an opposite view). The question addressed by these articles is whether a member of University staff should be open about mental health issues or not. The latest comes down firmly on “no” side. Although I understand the argument, I disagree very strongly with this conclusion.

In fact I’ve taken this a bit further than just disclosing my problems to my employer; I’ve even blogged about them, both here and elsewhere. I also stood up in the University of Sussex Senate about two years ago and spoke about them there. That latter episode was in response to the attempts by some members of Senate to play down the extent of the violence and intimidation associated with a protest on campus that erupted into a full-scale riot on March 2013, accompanied by theft, vandalism and arson. Since violence is the root cause of my longstanding troubles I was incensed by the casual attitude some academics displayed about something that should never be tolerated. I don’t know whether my intervention had any effect on the discussion but I felt I had to make my point. It still troubles me, in fact, that the culprits have still not been brought to justice, and that some of them undoubtedly remain at large on campus even today.

Anyway, two full years have passed since then and I have received nothing but supportive comments from colleagues both in the School and among senior managers in the University.

When I applied for my current job at Sussex, it was just after I’d recovered from a serious breakdown. When I was offered the position, paperwork arrived that included a form on which to declare any health issues (including mental health). I have moved around several times in my career and have never made a declaration on such a form before, but this time I felt that I should especially because I was still taking medication then. I did wonder whether I might be declared unfit to take up a job that promised to have a fair share of stress associated with it. In the end, though, what happened was that I was put in touch with the Occupational Health department who offered their services if there was anything they could do to help. All these discussions were confidential.

I think it is very important that staff do declare problems with depression or other mental health issues. That’s the only way to be sure of getting the support you need. It’s also important for your colleagues to be able to put arrangements in place if you need to take some time off. On top of all that, employers need to learn how widespread such problems can be so they can try to deal with any factors that might exacerbate existing conditions, such as work-related stress.

Going back to the article in the Times Higher, though. I should say that I can understand the author’s reluctance. It took me twenty-five years so I am hardly in a position to criticise anyone! I was particularly struck by this section:

To disguise my illness, I try my best to be the very opposite of what depressed people are. I become the funniest, the smiliest and the most supportive colleague at work. At times, the performance succeeds and I feel a fleeting sense of being invincible. However, this feeling quickly dissipates and I am left feeling utterly alone, dark and lost. A colleague once said to me that she thought I was the most positive person she had ever met and that everyone enjoyed working with me. I couldn’t say anything to her in that moment. But if I was to speak my truth, it would have been to tell her that I was probably the darkest and saddest of her colleagues. That darkness frightens the hell out of me – so I keep it to myself.

That will ring very true to anyone who is living with mental illness; it becomes part of who you are, and it does mean that you find somethings very difficult or impossible that other people take for granted, no matter how effective your medication is. Putting on a brave face is just one way to avoid dealing with it, but it’s just a form of denial. Another common avoidance strategy is to make up fake excuses for absence from events that fill you with dread. I’ve done that a number of times over the years and although it provides short-term relief, it leaves you with a sense of shame at your own dishonesty that is damaging in the long run to your sense of self-worth and will only serve to give you a reputation for unreliability. The darkness can indeed be frightening but it does not follow that you should keep it to yourself. You should share it – not necessarily with friends and colleagues, who may not know how to help – but with compassionate and highly trained professional counsellors who really can help. It will also help your institution provide more and better assistance.

This is not to say that there isn’t a downside to being open about mental health issues. Now that my own genie is not only out of the bottle but all over the internet I do wonder what the future holds in store for my career beyond my current position. Then again I’m not at all sure what I want to happen. Only time will tell.

End of Term Balls

Posted in Biographical, Education with tags , , , , on April 18, 2015 by telescoper

I haven’t had time to post for the last couple of days because I’ve been too bust with end-of-term business (and pleasure). Yesterday (Friday) was the last day of teaching term and this week I had to get a lot of things finished because of various deadlines, as well as attending numerous meetings. It’s been quite an exhausting week, not just because of that but also because by tradition the two departments within the School of Mathematical and Physical Sciences at the University of Sussex, the Department of Mathematics and the Department of Physics & Astronomy, hold their annual Staff-Student Balls on consecutive days. When I arrived here just over two years ago I decided that I should attend both or neither, as to attend at only one would look like favouritism. In fact this is the third time I’ve attended both of them. Let no-one say I don’t take my obligations seriously.  It’s a tough job, but someone has to do it. Holding both balls so close together  poses some problems for a person of my age, but I coped and also tried to weigh them up relative to each other and see  which was  most impressive.

Actually, both were really well organized. The Mathematics Ball was held in the elegant Hilton Metropole hotel and the Physics one in the Holiday Inn, both on the seafront. As has been the case in previous years the Mathematics ball is a bit more refined and sedate, the Physics one a little more raucous. Also this year there was a very large difference in the number of people going, with over 200 at the Physics Ball and only just over half that number at the Mathematics one. In terms of all-round fun I have to declare the Physics Ball the winner last year, but both occasions were very enjoyable. I’d like to say a very public thank you to the organizers of both events, especially Sinem and Jordan for Mathematics and Francis for Physics. Very well done.

The highlight of the Physics Ball was an after-dinner speech by particle physicist Jon Butterworth, who has an excellent blog called Life and Physics on the Guardian website. I’ve actually been in contact with Jon many times through social media (especially Twitter) over a period of over six years, but we never actually met in person until last night. I think he was a bit nervous beforehand because he had never done an after-dinner speech before, in the end though his talk was funny and wise, and extremely well received. Mind you, I did make it easy for him by giving a short speech to introduce him, and after a speech by me almost anyone would look good!

Thereafter the evening continued with drinking and dancing. After a while most people present were rather tired and emotional.  I even think some might even have been drunk. I eventually got home about 2am, after declining an invitation to go to the after-party. I’m far too old for that sort of thing. Social events like this can be a little bit difficult, for a number of reasons. One is that there’s an inevitable “distance” between students and staff, not just in terms of age but also in the sense that the staff have positions of responsibility for the students. Students are not children, of course, so we’re not legally  in loco parentis, but something of that kind of relationship is definitely there. Although it doesn’t stop either side letting their hair down once in a while, I always find there’s a little bit of tension especially if the revels get a bit out of hand. To help occasions like this run smoothly I think it’s the responsibility of the staff members present to drink heavily in order to put the students at ease. United by a common bond of inebriation, the staff-student divide crumbles and a good time is had by all.

There’s another thing I find a bit strange. Chatting to students last night was the first time I had spoken to many of my students like that, i.e. outside the lecture  or tutorial. I see the same faces in my lectures day in, day out but all I do is talk to them about physics. I really don’t know much about them at all. But it is especially nice when on occasions like this students come up, as several did last night, and say that they enjoyed my lectures. Actually, it’s more than just nice. Amid all the bureaucracy and committee meetings, it’s very valuable to be reminded what the job is really all about.

 

P.S. Apologies for not having any pictures. I left my phone in the office on Friday when I went home to get changed. I will post some if anyone can supply appropriate images. Or, better still, inappropriate ones!

 

 

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